Surface protection sheet

Abstract

The present invention provides surface protection sheet 10 comprising support substrate 1 and pressure-sensitive adhesive layer 2 provided on support substrate 1 . The pressure-sensitive adhesive constituting pressure-sensitive adhesive layer 2 comprises a polyisobutylene as its base polymer and a styrene/isobutylene block copolymer. The styrene/isobutylene block copolymer is contained in an amount larger than zero part by mass, but smaller than or equal to 70 parts by mass relative to 100 parts by mass of the polyisobutylene.

What is claimed is: 
     
         1 . A surface protection sheet comprising a substrate and a layer of a pressure-sensitive adhesive provided thereon,
 wherein the pressure-sensitive adhesive comprises:   a polyisobutylene as a base polymer; and   a styrene/isobutylene block copolymer, and   the amount of the styrene/isobutylene block copolymer in the pressure-sensitive adhesive is larger than zero part by mass, but smaller than or equal to 70 parts by mass relative to 100 parts by mass of the polyisobutylene.   
     
     
         2 . The surface protection sheet according to  claim 1 , wherein the styrene/isobutylene block copolymer primarily comprises a triblock copolymer having a structure of styrene block-isobutylene block-styrene block. 
     
     
         3 . The surface protection sheet according to  claim 1 , wherein the pressure-sensitive adhesive exhibits a room temperature storage modulus A when measured at a frequency of 10 Hz and a temperature of 23° C., and a high temperature storage modulus B when measured at a frequency of 10 Hz and a temperature of 23° C., with the storage moduli A and B satisfying the next inequality:
     A/B< 1.3. 
 
     
     
         4 . The surface protection sheet according to  claim 1 , wherein the pressure-sensitive adhesive exhibits a room temperature storage modulus A of 4.5×10 5  Pa or lower when measured at a frequency of 10 Hz and a temperature of 23° C. 
     
     
         5 . The surface protection sheet according to  claim 1 , wherein the polyisobutylene has a weight average molecular weight in a range from 30×10 4  to 150×10 4 . 
     
     
         6 . The surface protection sheet according to  claim 1 , wherein the styrene/isobutylene block copolymer has a weight average molecular weight in a range from 3×10 4  to 20×10 4 . 
     
     
         7 . The surface protection sheet according to  claim 2 , wherein the pressure-sensitive adhesive exhibits a room temperature storage modulus A when measured at a frequency of 10 Hz and a temperature of 23° C., and a high temperature storage modulus B when measured at a frequency of 10 Hz and a temperature of 23° C., with the storage moduli A and B satisfying the next inequality:
     A/B< 1.3. 
 
     
     
         8 . The surface protection sheet according to  claim 2 , wherein the pressure-sensitive adhesive exhibits a room temperature storage modulus A of 4.5×10 5  Pa or lower when measured at a frequency of 10 Hz and a temperature of 23° C. 
     
     
         9 . The surface protection sheet according to  claim 2 , wherein the polyisobutylene has a weight average molecular weight in a range from 30×10 4  to 150×10 4 . 
     
     
         10 . The surface protection sheet according to  claim 2 , wherein the styrene/isobutylene block copolymer has a weight average molecular weight in a range from 3×10 4  to 20×10 4 . 
     
     
         11 . The surface protection sheet according to  claim 3 , wherein the pressure-sensitive adhesive exhibits the room temperature storage modulus A of 4.5×10 5  Pa or lower. 
     
     
         12 . The surface protection sheet according to  claim 3 , wherein the polyisobutylene has a weight average molecular weight in a range from 30×10 4  to 150×10 4 . 
     
     
         13 . The surface protection sheet according to  claim 3 , wherein the styrene/isobutylene block copolymer has a weight average molecular weight in a range from 3×10 4  to 20×10 4 . 
     
     
         14 . The surface protection sheet according to  claim 4 , wherein the polyisobutylene has a weight average molecular weight in a range from 30×10 4  to 150×10 4 . 
     
     
         15 . The surface protection sheet according to  claim 4 , wherein the styrene/isobutylene block copolymer has a weight average molecular weight in a range from 3×10 4  to 20×10 4 . 
     
     
         16 . The surface protection sheet according to  claim 5 , wherein the styrene/isobutylene block copolymer has a weight average molecular weight in a range from 3×10 4  to 20×10 4 .